The present disclosure relates to a portable backscatter imaging inspection apparatus and an imaging method thereof, the apparatus comprising: an apparatus housing, an X-ray source, a rotating modulation mechanism, a radiation detector, a motion sensor and a controller; the X-ray source, the rotating modulation mechanism, the radiation detector and the motion sensor are disposed within the apparatus housing, wherein the radiation detector is used to receive scatter signal data from a surface of an object under inspection to form a two dimensional (2D) image, the motion sensor is used to collect a three dimensional (3D) motion track and scanning angles of the apparatus during a scanning process, the controller is used to splice and fuse a plurality of 2D images received by the radiation detector based on the 3D motion track and the scanning angles to obtain a stereo image of the surface of the object under inspection. This disclosure may achieve a better scan imaging effect on an object having a curved surface or multiple irregular surfaces.